CVE-2025-26465 Openssh: machine-in-the-middle attack if verifyhostkeydns is enabled
Attackers can bypass host key verification via MITM if VerifyHostKeyDNS is enabled and memory is exhausted, requiring patched OpenSSH versions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-26465?
CVE-2025-26465 is a medium-severity vulnerability in Debian Debian Linux, published on 18 Feb 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. A machine-in-the-middle attack can be performed by a malicious machine impersonating a legit server. This issue occurs due to how OpenSSH mishandles error codes in specific conditions when verifying the host key. For an attack to be considered successful, the attacker needs to manage to exhaust the client's memory resource first, turning the attack complexity high.
Weakness: CWE-390
Which versions are affected by CVE-2025-26465?
It affects 6 products.
Linux distribution packages (40)
openssh AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
openssh-askpass AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
openssh-cavs AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
openssh-clients AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
openssh-keycat AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
openssh-ldap AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
openssh-server AlmaLinux:8 | All versions | 8.0p1-26.el8_10 |
pam_ssh_agent_auth AlmaLinux:8 | All versions | 0.10.3-7.26.el8_10 |
openssh AlmaLinux:9 | All versions | 8.7p1-45.el9 |
openssh-askpass AlmaLinux:9 | All versions | 8.7p1-45.el9 |
openssh-clients AlmaLinux:9 | All versions | 8.7p1-45.el9 |
openssh-keycat AlmaLinux:9 | All versions | 8.7p1-45.el9 |
openssh-server AlmaLinux:9 | All versions | 8.7p1-45.el9 |
pam_ssh_agent_auth AlmaLinux:9 | All versions | 0.10.4-5.45.el9 |
openssh-askpass Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-askpass-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-cavs-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-clients-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-debugsource Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-keycat-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-ldap-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
openssh-server-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:8.0p1-26.el8_10 |
pam_ssh_agent_auth-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:0.10.3-7.26.el8_10 |
openssh Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-askpass-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-cavs Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-cavs-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-clients Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-clients-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-debugsource Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-keycat Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-keycat-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-ldap Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-ldap-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-server Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
openssh-server-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.0p1-26.el8_10 |
pam_ssh_agent_auth Red Hat:enterprise_linux:8::baseos | All versions | 0:0.10.3-7.26.el8_10 |
pam_ssh_agent_auth-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:0.10.3-7.26.el8_10 |
Products include Debian Debian Linux, Netapp Active Iq Unified Manager, Netapp Ontap, OpenSSH, Redhat Enterprise Linux, Redhat Openshift Container Platform.
How do I fix CVE-2025-26465?
Apply the vendor's patch.
Is CVE-2025-26465 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-26465 exists.
Public exploit code: 2 proofs of concept on GitHub.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2025-26465, ALSA-2025:16823, ALSA-2025:6993, AZL-56891, AZL-56894, BELL-CVE-2025-26465 and 26 more.